Chapter 15 Light and Optics - Part I Flashcards
Luminous
producing visible light.
LED
semiconductor device that emits light
when current passes through it in one direction
but not the other.
Light intensity
the light source’s power, brightness, aka the rate at which it radiates energy.
Candela
an SI unit of light intensity
Illumination of an object is ____ to the intensity of the light source (e.g., more intense light source brings greater illumination)
Inverse Square Law
proportional
illumination is inversely proportional to the square of the distance from the light source,
(so that moving twice as far from a lamp reduces the illumination to one-fourth the original amount).
What spectroscopes can observe.
continuous spectra and line spectra.
phosphorescence
(like with glow-in-the-dark stickers)
emits visible light even after the energy source/photons is/are removed. (e.g., they can glow in the dark)
A vacuum cleaner can appear to be a different color to different people because…
“One’s eyes and brain determine how this EM (electromagnetic) energy is perceived.”
incandescent light
(like the sun)
light produced by materials heated until they glow.
(some of the thermal energy is converted to EM energy which radiates).
The sun is approx 8.3 ___ ____ away.
light minutes.
(the distance light travels in a minute).
Light years (“ly”)
the distance light travels in a year.
bioluminescence
cold light produced by living things.
ROYGBIV
red, orange, yellow, green, blue, indigo, violet
flourescence
(like flourescent tubes that have mercury gas which becomes plasma when electricity passes through).
A substance that radiates visible light as it absorbs a higher-energy form of EM energy (like UV), but stops glowing when photons aren’t available.
Qualities of/uses for coherent light
(
very bright,
monochromatic light,
used in lasers
